Library Dues: can't get History of Life Magic

I need to get the History of Life Magic to complete the Library Dues quest. However, even though I've defeated Lady Blackhope before, I can no longer go into her tower - it isn't active. Is there any way to get it? I was able to do this for History of Storm Magic and re-enter the Harvest Lord Tower again.

I need to get the History of Life Magic to complete the Library Dues quest. However, even though I've defeated Lady Blackhope before, I can no longer go into her tower - it isn't active. Is there any way to get it? I was able to do this for History of Storm Magic and re-enter the Harvest Lord Tower again.

Please help

that sounds like a glitch; you should be able to re-enter any dungeon (and this isn't even a real dungeon) you've already done. Might want to drop support a line and let them know that you are unable to complete this quest due to this error.